The present disclosure relates to a microelectronic component and to a corresponding production process.
Micromechanical sensors, for example inertial sensors, are usually implemented by means of capacitive or piezoresistive transducers. In the literature, there have for some time been reports of what are called moving-gate inertial sensors, although no such sensors are available on the market to date. One reason for this is the way in which the transducer element is produced, more particularly the provision of a suitable sacrificial layer operation and the availability of CMOS layers with suitable, well-defined mechanical or thermomechanical properties.
Typically, the sacrificial layer used in micromechanics is silicon oxide. In the case of moving-gate inertial sensors, however, the channel region and the source/drain contacts would be open and unprotected, since the thin gate oxide is inevitably also removed when the sacrificial layer is removed. Thus, the channel region would then be open and unprotected, as would the pn junctions between source/drain region and channel region. The result is generation of surface states which disrupt the operating range of the field-effect transistor or lead to drift and noise, and make the sensor element unreliable.
EP 0 990 911 A1 describes a micromechanical field-effect-based sensor and the use thereof, wherein a gate region is movable with respect to the source and drain region.
US 2009/0317930 A1 describes a method for producing a structure having a mobile element by means of a heterogeneous sacrificial layer.
US 2011/0265574 A1 describes a system comprising micromechanical functional elements and CMOS devices.
DE 10 2009 029 217 A1 describes an inertial sensor comprising a field-effect transistor, wherein the gate electrode is fixed and the channel region is formed and arranged so as to be movable.